| 摘要 |
To rotate a pipe (17) to be urged into the ground, a rotary disk (20) clamped at said pipe (17) is pivotable on a table (19) which carries two groups of driving cylinders (40, 41). While the first group is operative to carry out the working stroke in order to turn the rotary disk (20) the return stroke is performed by the second group thus ensuring a continuous rotation of the rotary disk (20) or a standstill in one sense of rotation.
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